Various apparatus are employed for arranging sheet material in a package suitable for use or sale in commerce. One such apparatus, useful for describing the teachings of the present invention, is a mailpiece inserter system employed in the fabrication of high volume mail communications, e.g., mass mailings. Such mailpiece inserter systems are typically used by organizations such as banks, insurance companies and utility companies for producing a large volume of specific mail communications where the contents of each mailpiece are directed to a particular addressee. Also, other organizations, such as direct mailers, use mail inserters for producing mass mailings where the contents of each mailpiece are substantially identical with respect to each addressee. Examples of inserter systems are the 8 series, 9 series, and APS™ inserter systems available from Pitney Bowes Inc. located in Stamford, Conn., USA.
In many respects, a typical inserter system resembles a manufacturing assembly line. Sheets and other raw materials (i.e., a web of paper stock, enclosures, and envelopes) enter the inserter system as inputs. Various modules or workstations in the inserter system work cooperatively to process the sheets until a finished mailpiece is produced. The precise configuration of each inserter system depends upon the needs of each customer or installation.
Typically, inserter systems prepare mailpieces by arranging preprinted sheets of material into a collation, i.e., the content material of the mailpiece, on a transport deck. The collation of preprinted sheet may continue to a chassis module where additional sheets or inserts may be added to a targeted audience of mailpiece recipients. From the chassis module, the fully developed collation may continue to a stitcher module where the sheet material may be stitched, stapled, or otherwise bound. Subsequently, the bound collation is typically folded and placed into envelopes. Once filled, the envelopes are conveyed to yet other stations for further processing. That is, the envelopes may be closed, sealed, weighed, sorted and stacked. Additionally, the inserter may include a postage meter for applying postage indicia based upon the weight and/or size of the mailpiece.
The mailpiece collation may comprise several individualized documents, i.e., specific to a mailpiece addressee, and/or one or more preprinted inserts which may be specifically tailored to the addressee. Generally, a barcode system is employed to command various sheet feeding mechanisms (i.e., one of the components of the chassis module mentioned in the preceding paragraph) to feed/add a particular insert to a collation. Of course, the mailpiece collation may comprise any combination of sheet material, whether they include personalized documents, preprinted inserts or a combination thereof.
FIGS. 1a-1c show the relevant components of a prior art chassis module/station 100 of an inserter system. The figures show the chassis module 100 conveying a sheet material 112 along a transport deck 114 (omitted from FIG. 1a to reveal underlying components). The transport deck 114 includes a drive mechanism 116 for displacing the sheet material 112 as it slides over the transport deck 114. In FIG. 1c, the transport deck 114 includes a low friction surface 114S having a pair of parallel grooves or slots 114G formed therein. Riding in the grooves or through the slots 114G are fingers 116F which extend orthogonally from the surface 114S of the deck 114.
Referring to FIGS. 1a-1c, the fingers 116F are driven by a belt or chain 118C1, which in turn wraps around a drive sprocket or gear 118G. Furthermore, the fingers 116F1 are spaced in equal length increments while the fingers 116F2, of adjacent chains 118C1, 118C2 are substantially aligned, i.e., laterally across the transport deck 114. As such, a substantially rectangular region or pocket is established between the fingers 116F1, 116F2.
Above the transport deck 114 are one or more feeder mechanisms 120A, 120B (two are shown for illustration purposes) which are capable of feeding inserts 122, i.e., sheet material, to the transport deck 114. The inserts 122 may be laid to build a collation 112 or may be added to the sheet material 112 (i.e., a partial collation) initiated upstream of the transport deck 114. A controller (not shown) issues command signals to the feeder mechanisms 120A, 120B to appropriately time the feed sequence such that the inserts 122 are laid in the rectangular region 124 between the fingers 116F1, 116F2. More specifically, as each pair of lateral fingers 116F1, 116F2 is driven within the grooves or slots 144G, one edge of the sheet material 112 is engaged to slide the collation 112 along the transport deck 114. As the sheet material 112 passes below the feeding mechanisms 120A, 120B, other sheets or inserts 122 are added. At the end of the transport deck 114, the fingers 116F1, 116F2 drop beneath the transport deck 114 such that the collation (i.e., the combination of the sheet material and inserts 122) may proceed to subsequent processing stations.
While the drive mechanism 116 of the prior art provides rapid transport of collated sheet material 112, 122 and has proven to be effective and reliable, sheets or inserts 122 fed by the feeding mechanisms 120A, 120B can become misaligned in the rectangular space or pocket 124 provided between the fingers 116F1, 116F2. That is, inasmuch as the pocket 124 is oversized to accept the sheets or inserts 122, the inserts 122 can become misaligned due to a lack of positive registration surfaces on all sides of the collation 112, 122.
Various mechanisms are employed to vary the pocket size, i.e., sometimes referred to as the “pitch”, between the chassis fingers. The ability to change pitch not only enables greater efficiency, i.e., a greater number of pockets for inserts, but also minimizes the misalignment of inserts being laid on a collation. Notwithstanding the ability to minimize pocket size, it will be appreciated that without positive restraint on all free edges of the collation, individual sheets or inserts will be misaligned. Consequently, prior art inserters commonly employ complex registration mechanisms or jogging devices to align the free edges of a collation. For example, inserters may employ a series of swing arms which pivot onto the transport deck, i.e., into the conveyance path of the collation. The swing arms engage and align the leading edge of a collation, i.e., the edge opposite the fingers. While the swing arms effectively maintain alignment of the collation, the mechanical complexity associated with the pivoting mechanism is a regular source of maintenance, jamming or failure.
In the absence of such swing arms, an inserter may employ other jogging mechanisms downstream of the chassis module to align the edges of the collation. That is, before subsequent processing, e.g., stitching or enveloping, the edges of the collation are aligned to: (i) ensure that stitching does not result in permanent misalignment of the collation or (ii) provide a smooth transition and/or snug fit within a mailing envelope. Such jogging mechanisms often employ a complex arrangement of solenoid activated stops which tap or “jog” each edge by a predetermined displacement with each motion of the stop. By jogging the stops several times, the edges of the collation are aligned. Like the swing arm mechanisms described above, the jogging mechanisms are highly complex and prone to increased maintenance, jamming and failure.
A need, therefore, exists for a transport system for sheet material which eliminates mechanical complexity, enhances reliability and minimizes maintenance.